#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
using namespace std;
int main()
{
    double n = 0;
    cin >> n;
    double l = -1000;
    double r = 1000;
    double mid = 0;
    do
    {
        mid = (l + r) / 2;

        if (mid * mid * mid > n) r = mid;
        else l = mid;

    } while (r - l >= 1e-7);
    printf("%lf", l);
    return 0;
}